How can you give an account from the outside that someone is have nightmare?

How can you give an account from the outside that someone is have nightmare?
Watch for rapid, jerk eye movements that indicate REM sleep. That means the creature is dreaming. As far as whether it's a good dream or a discouraging dream, however, I don't think in that is any way to speak about -- except by waking the character and asking him or her.
I don't think you can - you would own to ask them. Unless they are screaming in their sleep!!
You should be INSIDE, you'd enjoy a better chance of knowing.
ask professor Xavier of the X-men, or Jean Grey. they know how. :)